1
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Gladieux P, van Oosterhout C, Fairhead S, Jouet A, Ortiz D, Ravel S, Shrestha RK, Frouin J, He X, Zhu Y, Morel JB, Huang H, Kroj T, Jones JDG. Extensive immune receptor repertoire diversity in disease-resistant rice landraces. Curr Biol 2024:S0960-9822(24)01000-5. [PMID: 39146939 DOI: 10.1016/j.cub.2024.07.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/19/2024] [Accepted: 07/16/2024] [Indexed: 08/17/2024]
Abstract
Plants have powerful defense mechanisms and extensive immune receptor repertoires, yet crop monocultures are prone to epidemic diseases. Rice (Oryza sativa) is susceptible to many diseases, such as rice blast caused by Magnaporthe oryzae. Varietal resistance of rice to blast relies on intracellular nucleotide binding, leucine-rich repeat (NLR) receptors that recognize specific pathogen molecules and trigger immune responses. In the Yuanyang terraces in southwest China, rice landraces rarely show severe losses to disease whereas commercial inbred lines show pronounced field susceptibility. Here, we investigate within-landrace NLR sequence diversity of nine rice landraces and eleven modern varieties using complexity reduction techniques. We find that NLRs display high sequence diversity in landraces, consistent with balancing selection, and that balancing selection at NLRs is more pervasive in landraces than modern varieties. Notably, modern varieties lack many ancient NLR haplotypes that are retained in some landraces. Our study emphasizes the value of standing genetic variation that is maintained in farmer landraces as a resource to make modern crops and agroecosystems less prone to disease. The conservation of landraces is, therefore, crucial for ensuring food security in the face of dynamic biotic and abiotic threats.
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Affiliation(s)
- Pierre Gladieux
- Plant Health Institute Montpellier, University of Montpellier, INRAE, CIRAD, IRD, Institut Agro, 34398 Montpellier, France.
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Sebastian Fairhead
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Agathe Jouet
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Diana Ortiz
- Plant Health Institute Montpellier, University of Montpellier, INRAE, CIRAD, IRD, Institut Agro, 34398 Montpellier, France
| | - Sebastien Ravel
- Plant Health Institute Montpellier, University of Montpellier, INRAE, CIRAD, IRD, Institut Agro, 34398 Montpellier, France
| | - Ram-Krishna Shrestha
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Julien Frouin
- CIRAD, UMR AGAP Institut, 34398 Montpellier, France; UMR AGAP Institut, Université de Montpellier, CIRAD, INRAE, Institut Agro, 34398 Montpellier, France
| | - Xiahong He
- School of Landscape and Horticulture, Southwest Forestry University, Kunming 650233, China
| | - Youyong Zhu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China; Key Laboratory of Agro-Biodiversity and Pest Management of Education Ministry of China, Yunnan Agricultural University, Kunming 650201, China
| | - Jean-Benoit Morel
- Plant Health Institute Montpellier, University of Montpellier, INRAE, CIRAD, IRD, Institut Agro, 34398 Montpellier, France
| | - Huichuan Huang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China; Key Laboratory of Agro-Biodiversity and Pest Management of Education Ministry of China, Yunnan Agricultural University, Kunming 650201, China.
| | - Thomas Kroj
- Plant Health Institute Montpellier, University of Montpellier, INRAE, CIRAD, IRD, Institut Agro, 34398 Montpellier, France.
| | - Jonathan D G Jones
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK.
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2
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Phillips KP, Cable J, Mohammed RS, Chmielewski S, Przesmycka KJ, van Oosterhout C, Radwan J. Functional immunogenetic variation, rather than local adaptation, predicts ectoparasite infection intensity in a model fish species. Mol Ecol 2021; 30:5588-5604. [PMID: 34415650 PMCID: PMC9292977 DOI: 10.1111/mec.16135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/07/2021] [Accepted: 08/11/2021] [Indexed: 11/28/2022]
Abstract
Natural host populations differ in their susceptibility to infection by parasites, and these intrapopulation differences are still an incompletely understood component of host‐parasite dynamics. In this study, we used controlled infection experiments with wild‐caught guppies (Poecilia reticulata) and their ectoparasite Gyrodactylus turnbulli to investigate the roles of local adaptation and host genetic composition (immunogenetic and neutral) in explaining differences in susceptibility to infection. We found differences between our four study host populations that were consistent between two parasite source populations, with no indication of local adaptation by either host or parasite at two tested spatial scales. Greater values of host population genetic variability metrics broadly aligned with lower population mean infection intensity, with the best alignments associated with major histocompatibility complex (MHC) “supertypes”. Controlling for intrapopulation differences and potential inbreeding variance, we found a significant negative relationship between individual‐level functional MHC variability and infection: fish carrying more MHC supertypes experienced infections of lower severity, with limited evidence for supertype‐specific effects. We conclude that population‐level differences in host infection susceptibility probably reflect variation in parasite selective pressure and/or host evolutionary potential, underpinned by functional immunogenetic variation.
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Affiliation(s)
- Karl P Phillips
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.,School of Biological Earth & Environmental Sciences, University College Cork, Cork, Ireland.,Marine Institute, Newport, Co. Mayo, Ireland
| | - Joanne Cable
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Ryan S Mohammed
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.,Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Sebastian Chmielewski
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
| | - Karolina J Przesmycka
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Jacek Radwan
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
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3
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Biedrzycka A, Popiołek M, Zalewski A. Host-parasite interactions in non-native invasive species are dependent on the levels of standing genetic variation at the immune locus. BMC Evol Biol 2020; 20:43. [PMID: 32299345 PMCID: PMC7164242 DOI: 10.1186/s12862-020-01610-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 04/06/2020] [Indexed: 12/21/2022] Open
Abstract
Background Parasites may mediate the success of biological invasions through their effect on host fitness and thus, on host population growth and stability. However, a release from the pressure of parasites is strongly related to the genetic differentiation of the host. In invasive host populations, the number of available genetic variants, allowing them to ‘fight’ the infection, are likely to be influenced by founder events and genetic drift. The level standing genetic variation of invasive populations may be crucial in successfully adapting to new environments and resisting diseases. We studied invasive populations of raccoon that experienced a random reduction in genetic diversity during the establishment and evaluated the relationship between host immune genetic diversity and intestinal parasites infection. Results We distinguished two different genetic clusters that are characterized by different sets of functionally relevant MHC-DRB alleles. Both clusters were characterized by considerably different allele-parasite associations and different levels of parasite infection. The specific resistance MHC-DRB alleles explained the lower prevalence of Digenea parasites. An increased infection intensity was related to the presence of two MHC-DRB alleles. One of these alleles significantly decreased in frequency over time, causing a decrease of Digenea abundance in raccoons in consecutive years. Conclusions Our findings suggest that intestinal parasites can exert selective pressure on an invasive host with lowered levels of immune genetic diversity and contribute to promoting local adaptation over time. The random genetic drift that created the two different genetic clusters in the invasive raccoon range imposed completely different MHC-parasite associations, strongly associated with the infection status of populations. Our findings underline the role of standing genetic variation in shaping host-parasite relationships and provide empirical support that functional genetic variation may be, at least partly, responsible for differences in the success of invasive populations.
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Affiliation(s)
- Aleksandra Biedrzycka
- Institute of Nature Conservation, Polish Academy of Sciences, Al. Adama Mickiewicza 33, 31-120, Kraków, Poland.
| | - Marcin Popiołek
- Department of Parasitology, Institute of Genetics and Microbiology, University of Wrocław, Przybyszewskiego 63/67, 51-148, Wroclaw, Poland
| | - Andrzej Zalewski
- Mammal Research Institute, Polish Academy of Sciences, ul. Stoczek 1, 17-230, Białowieża, Poland
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4
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McMullan M, Rafiqi M, Kaithakottil G, Clavijo BJ, Bilham L, Orton E, Percival-Alwyn L, Ward BJ, Edwards A, Saunders DGO, Garcia Accinelli G, Wright J, Verweij W, Koutsovoulos G, Yoshida K, Hosoya T, Williamson L, Jennings P, Ioos R, Husson C, Hietala AM, Vivian-Smith A, Solheim H, MaClean D, Fosker C, Hall N, Brown JKM, Swarbreck D, Blaxter M, Downie JA, Clark MD. The ash dieback invasion of Europe was founded by two genetically divergent individuals. Nat Ecol Evol 2018; 2:1000-1008. [PMID: 29686237 PMCID: PMC5969572 DOI: 10.1038/s41559-018-0548-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 03/27/2018] [Indexed: 11/22/2022]
Abstract
Accelerating international trade and climate change make pathogen spread an increasing concern. Hymenoscyphus fraxineus, the causal agent of ash dieback, is a fungal pathogen that has been moving across continents and hosts from Asian to European ash. Most European common ash trees (Fraxinus excelsior) are highly susceptible to H. fraxineus, although a minority (~5%) have partial resistance to dieback. Here, we assemble and annotate a H. fraxineus draft genome which approaches chromosome scale. Pathogen genetic diversity across Europe and in Japan, reveals a strong bottleneck in Europe, though a signal of adaptive diversity remains in key host interaction genes. We find that the European population was founded by two divergent haploid individuals. Divergence between these haplotypes represents the ancestral polymorphism within a large source population. Subsequent introduction from this source would greatly increase adaptive potential of the pathogen. Thus, further introgression of H. fraxineus into Europe represents a potential threat and Europe-wide biological security measures are needed to manage this disease.
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Affiliation(s)
- Mark McMullan
- The Earlham Institute, Norwich Research Park, Norwich, UK.
| | | | | | | | | | | | | | - Ben J Ward
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | - Anne Edwards
- John Innes Centre, Norwich Research Park, Norwich, UK
| | | | | | | | - Walter Verweij
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | | | - Kentaro Yoshida
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK.,Graduate school of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Tsuyoshi Hosoya
- Department of Botany, National Museum of Nature and Science, Tsukuba, Ibaraki, Japan
| | | | | | - Renaud Ioos
- ANSES Laboratoire de la Santé des Végétaux, Malzéville, France
| | | | - Ari M Hietala
- Norwegian Institute of Bioeconomy Research, Ås, Norway
| | | | | | - Dan MaClean
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | | | - Neil Hall
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | | | | | - Mark Blaxter
- Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh, UK.,Edinburgh Genomics, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | | | - Matthew D Clark
- The Earlham Institute, Norwich Research Park, Norwich, UK. .,Department of Life Sciences, Natural History Museum, London, UK.
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5
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Lighten J, Papadopulos AST, Mohammed RS, Ward BJ, G Paterson I, Baillie L, Bradbury IR, Hendry AP, Bentzen P, van Oosterhout C. Evolutionary genetics of immunological supertypes reveals two faces of the Red Queen. Nat Commun 2017; 8:1294. [PMID: 29101318 PMCID: PMC5670221 DOI: 10.1038/s41467-017-01183-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 08/23/2017] [Indexed: 11/09/2022] Open
Abstract
Red Queen host-parasite co-evolution can drive adaptations of immune genes by positive selection that erodes genetic variation (Red Queen arms race) or results in a balanced polymorphism (Red Queen dynamics) and long-term preservation of genetic variation (trans-species polymorphism). These two Red Queen processes are opposite extremes of the co-evolutionary spectrum. Here we show that both Red Queen processes can operate simultaneously by analysing the major histocompatibility complex (MHC) in guppies (Poecilia reticulata and P. obscura) and swamp guppies (Micropoecilia picta). Sub-functionalisation of MHC alleles into 'supertypes' explains how polymorphisms persist during rapid host-parasite co-evolution. Simulations show the maintenance of supertypes as balanced polymorphisms, consistent with Red Queen dynamics, whereas alleles within supertypes are subject to positive selection in a Red Queen arms race. Building on the divergent allele advantage hypothesis, we show that functional aspects of allelic diversity help to elucidate the evolution of polymorphic genes involved in Red Queen co-evolution.
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Affiliation(s)
- Jackie Lighten
- School of Environmental Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK.
| | - Alexander S T Papadopulos
- Molecular Ecology and Fisheries Genetics Laboratory, Environment Centre Wales, School of Biological Sciences, Bangor University, Bangor, LL57 2UW, UK
| | - Ryan S Mohammed
- Department of Life Sciences, The University of the West Indies, St Augustine, Trinidad and Tobago
| | - Ben J Ward
- Earlham Institute, Norwich Research Park Innovation Centre, Colney Lane, Norwich, NR4 7UZ, UK
| | - Ian G Paterson
- Marine Gene Probe Laboratory, Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada, B3H 4R2
| | - Lyndsey Baillie
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, Canada, V6T 1Z4
| | - Ian R Bradbury
- Marine Gene Probe Laboratory, Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada, B3H 4R2.,Science Branch, Department of Fisheries and Oceans Canada, 80 East White Hills Road, St. John's, NL, Canada, A1C 5X1
| | - Andrew P Hendry
- McGill University, 859 Sherbrooke Street West, Montreal, QC, Canada, H3A 0C4.,Redpath Museum, McGill University, 859 Sherbrooke Street West, Montreal, QC, Canada, H3A 0C4
| | - Paul Bentzen
- Marine Gene Probe Laboratory, Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada, B3H 4R2
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK.
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6
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Santonastaso T, Lighten J, van Oosterhout C, Jones KL, Foufopoulos J, Anthony NM. The effects of historical fragmentation on major histocompatibility complex class II β and microsatellite variation in the Aegean island reptile, Podarcis erhardii. Ecol Evol 2017; 7:4568-4581. [PMID: 28690787 PMCID: PMC5496512 DOI: 10.1002/ece3.3022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 03/16/2017] [Accepted: 03/27/2017] [Indexed: 01/29/2023] Open
Abstract
The major histocompatibility complex (MHC) plays a key role in disease resistance and is the most polymorphic gene region in vertebrates. Although habitat fragmentation is predicted to lead to a loss in MHC variation through drift, the impact of other evolutionary forces may counter this effect. Here we assess the impact of selection, drift, migration, and recombination on MHC class II and microsatellite variability in 14 island populations of the Aegean wall lizard Podarcis erhardii. Lizards were sampled from islands within the Cyclades (Greece) formed by rising sea levels as the last glacial maximum approximately 20,000 before present. Bathymetric data were used to determine the area and age of each island, allowing us to infer the corresponding magnitude and timing of genetic bottlenecks associated with island formation. Both MHC and microsatellite variation were positively associated with island area, supporting the hypothesis that drift governs neutral and adaptive variation in this system. However, MHC but not microsatellite variability declined significantly with island age. This discrepancy is likely due to the fact that microsatellites attain mutation‐drift equilibrium more rapidly than MHC. Although we detected signals of balancing selection, recombination and migration, the effects of these evolutionary processes appeared negligible relative to drift. This study demonstrates how land bridge islands can provide novel insights into the impact of historical fragmentation on genetic diversity as well as help disentangle the effects of different evolutionary forces on neutral and adaptive diversity.
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Affiliation(s)
- Trent Santonastaso
- Department of Biological Sciences University of New Orleans New Orleans LA USA
| | - Jackie Lighten
- School of Environmental Sciences University of East Anglia Norwich Research Park Norwich UK
| | - Cock van Oosterhout
- School of Environmental Sciences University of East Anglia Norwich Research Park Norwich UK
| | - Kenneth L Jones
- Department of Biochemistry and Molecular Genetics University of Colorado Denver School of Medicine Denver CO USA
| | - Johannes Foufopoulos
- School of the Environment and Sustainability University of Michigan Ann Arbor MI USA
| | - Nicola M Anthony
- Department of Biological Sciences University of New Orleans New Orleans LA USA
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7
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Rico Y, Ethier DM, Davy CM, Sayers J, Weir RD, Swanson BJ, Nocera JJ, Kyle CJ. Spatial patterns of immunogenetic and neutral variation underscore the conservation value of small, isolated American badger populations. Evol Appl 2016; 9:1271-1284. [PMID: 27877205 PMCID: PMC5108218 DOI: 10.1111/eva.12410] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/14/2016] [Indexed: 12/29/2022] Open
Abstract
Small and isolated populations often exhibit low genetic diversity due to drift and inbreeding, but may simultaneously harbour adaptive variation. We investigate spatial distributions of immunogenetic variation in American badger subspecies (Taxidea taxus), as a proxy for evaluating their evolutionary potential across the northern extent of the species' range. We compared genetic structure of 20 microsatellites and the major histocompatibility complex (MHC DRB exon 2) to evaluate whether small, isolated populations show low adaptive polymorphism relative to large and well-connected populations. Our results suggest that gene flow plays a prominent role in shaping MHC polymorphism across large spatial scales, while the interplay between gene flow and selection was stronger towards the northern peripheries. The similarity of MHC alleles within subspecies relative to their neutral genetic differentiation suggests that adaptive divergence among subspecies can be maintained despite ongoing gene flow along subspecies boundaries. Neutral genetic diversity was low in small relative to large populations, but MHC diversity within individuals was high in small populations. Despite reduced neutral genetic variation, small and isolated populations harbour functional variation that likely contribute to the species evolutionary potential at the northern range. Our findings suggest that conservation approaches should focus on managing adaptive variation across the species range rather than protecting subspecies per se.
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Affiliation(s)
- Yessica Rico
- Forensic Science DepartmentTrent UniversityPeterboroughONCanada
- Natural Resources DNA Profiling and Forensics CentreTrent UniversityPeterboroughONCanada
- Present address: CONACYTInstituto de Ecología A.C.Centro Regional del BajíoAvenida Lázaro Cárdenas 253PátzcuaroMichoacán61600México
| | - Danielle M. Ethier
- Ontario Badger ProjectGuelphONCanada
- Department of Integrative BiologyUniversity of GuelphGuelphONCanada
| | - Christina M. Davy
- Forensic Science DepartmentTrent UniversityPeterboroughONCanada
- Natural Resources DNA Profiling and Forensics CentreTrent UniversityPeterboroughONCanada
| | | | - Richard D. Weir
- Ecosystems Protection & Sustainability BranchMinistry of EnvironmentVictoriaBCCanada
| | | | - Joseph J. Nocera
- Wildlife Research and Monitoring SectionMinistry of Natural Resources & ForestryPeterboroughONCanada
| | - Christopher J. Kyle
- Forensic Science DepartmentTrent UniversityPeterboroughONCanada
- Natural Resources DNA Profiling and Forensics CentreTrent UniversityPeterboroughONCanada
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8
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Fijarczyk A, Babik W. Detecting balancing selection in genomes: limits and prospects. Mol Ecol 2015; 24:3529-45. [DOI: 10.1111/mec.13226] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/27/2015] [Accepted: 04/30/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Anna Fijarczyk
- Institute of Environmental Sciences; Jagiellonian University; Gronostajowa 7 30-387 Kraków Poland
| | - Wiesław Babik
- Institute of Environmental Sciences; Jagiellonian University; Gronostajowa 7 30-387 Kraków Poland
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9
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Herdegen M, Babik W, Radwan J. Selective pressures on MHC class II genes in the guppy (Poecilia reticulata) as inferred by hierarchical analysis of population structure. J Evol Biol 2014; 27:2347-59. [PMID: 25244157 DOI: 10.1111/jeb.12476] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 11/29/2022]
Abstract
Genes of the major histocompatibility complex, which are the most polymorphic of all vertebrate genes, are a pre-eminent system for the study of selective pressures that arise from host-pathogen interactions. Balancing selection capable of maintaining high polymorphism should lead to the homogenization of MHC allele frequencies among populations, but there is some evidence to suggest that diversifying selection also operates on the MHC. However, the pattern of population structure observed at MHC loci is likely to depend on the spatial and/or temporal scale examined. Here, we investigated selection acting on MHC genes at different geographic scales using Venezuelan guppy populations inhabiting four regions. We found a significant correlation between MHC and microsatellite allelic richness across populations, which suggests the role of genetic drift in shaping MHC diversity. However, compared to microsatellites, more MHC variation was explained by differences between populations within larger geographic regions and less by the differences between the regions. Furthermore, among proximate populations, variation in MHC allele frequencies was significantly higher compared to microsatellites, indicating that selection acting on MHC may increase population structure at small spatial scales. However, in populations that have significantly diverged at neutral markers, the population-genetic signature of diversifying selection may be eradicated in the long term by that of balancing selection, which acts to preserve rare alleles and thus maintain a common pool of MHC alleles.
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Affiliation(s)
- M Herdegen
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
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10
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Tezuka A, Kasagi S, van Oosterhout C, McMullan M, Iwasaki WM, Kasai D, Yamamichi M, Innan H, Kawamura S, Kawata M. Divergent selection for opsin gene variation in guppy (Poecilia reticulata) populations of Trinidad and Tobago. Heredity (Edinb) 2014; 113:381-9. [PMID: 24690753 DOI: 10.1038/hdy.2014.35] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 12/03/2013] [Accepted: 02/24/2014] [Indexed: 11/09/2022] Open
Abstract
The guppy is known to exhibit remarkable interindividual variations in spectral sensitivity of middle to long wavelength-sensitive (M/LWS) cone photoreceptor cells. The guppy has four M/LWS-type opsin genes (LWS-1, LWS-2, LWS-3 and LWS-4) that are considered to be responsible for this sensory variation. However, the allelic variation of the opsin genes, particularly in terms of their absorption spectrum, has not been explored in wild populations. Thus, we examined nucleotide variations in the four M/LWS opsin genes as well as blue-sensitive SWS2-B and ultraviolet-sensitive SWS1 opsin genes for comparison and seven non-opsin nuclear loci as reference genes in 10 guppy populations from various light environments in Trinidad and Tobago. For the first time, we discovered a potential spectral variation (180 Ser/Ala) in LWS-1 that differed at an amino acid site known to affect the absorption spectra of opsins. Based on a coalescent simulation of the nucleotide variation of the reference genes, we showed that the interpopulation genetic differentiation of two opsin genes was significantly larger than the neutral expectation. Furthermore, this genetic differentiation was significantly related to differences in dissolved oxygen (DO) level, and it was not explained by the spatial distance between populations. The DO levels are correlated with eutrophication that possibly affects the color of aquatic environments. These results suggest that the population diversity of opsin genes is significantly driven by natural selection and that the guppy could adapt to various light environments through color vision changes.
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Affiliation(s)
- A Tezuka
- Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan
| | - S Kasagi
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan
| | - C van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - M McMullan
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - W M Iwasaki
- Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan
| | - D Kasai
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan
| | - M Yamamichi
- Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (Sokendai), Hayama, Japan
| | - H Innan
- Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (Sokendai), Hayama, Japan
| | - S Kawamura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan
| | - M Kawata
- Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan
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11
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Herdegen M, Alexander HJ, Babik W, Mavárez J, Breden F, Radwan J. Population structure of guppies in north-eastern Venezuela, the area of putative incipient speciation. BMC Evol Biol 2014; 14:28. [PMID: 24533965 PMCID: PMC3942120 DOI: 10.1186/1471-2148-14-28] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 02/10/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Geographic barriers to gene flow and divergence among populations in sexual traits are two important causes of genetic isolation which may lead to speciation. Genetic isolation may be facilitated if these two mechanisms act synergistically. The guppy from the Cumaná region (within the Cariaco drainage) of eastern Venezuela has been previously described as a case of incipient speciation driven by sexual selection, significantly differentiated in sexual colouration and body shape from the common guppy, Poecilia reticulata. The latter occurs widely in northern Venezuela, including the south-eastern side of Cordillera de la Costa, where it inhabits streams belonging to the San Juan drainage. Here, we present molecular and morphological analyses of differentiation among guppy populations in the Cariaco and San Juan drainages. Our analyses are based on a 953 bp long mtDNA fragment, a set of 15 microsatellites (519 fish from 20 populations), and four phenotypic traits. RESULTS Both microsatellite and mtDNA data showed that guppies inhabiting the two drainages are characterised by a significant genetic differentiation, but a higher proportion of the genetic variance was distributed among populations within regions. Most guppies in the Cariaco drainage had mtDNA from a distinct lineage, but we also found evidence for widespread introgression of mtDNA from the San Juan drainage into the Cariaco drainage. Phenotypically, populations in the two regions differed significantly only in the number of black crescents. Phenotypic clustering did not support existence of two distinct groupings, but indicated a degree of distinctiveness of Central Cumaná (CC) population. However, CC population showed little differentiation at the neutral markers from the proximate populations within the Cariaco drainage. CONCLUSIONS Our findings are consistent with only partial genetic isolation between the two geographic regions and indicate that the geographic barrier of Cordillera de la Costa has not played an important role in strengthening the incomplete pre-zygotic reproductive barrier between Cumaná and common guppy. Significant phenotypic differentiation between genetically similar (in terms of neutral variation) populations suggests that mate choice can maintain divergence at sexually selected traits despite gene flow. However, neither genetic nor phenotypic clustering supported delineation of two species within the region.
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Affiliation(s)
- Magdalena Herdegen
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, Krakow 30-387, Poland
| | - Heather J Alexander
- Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Wiesław Babik
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, Krakow 30-387, Poland
| | - Jesús Mavárez
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, Caracas 1020-A, Venezuela
- Laboratoire d’Ecologie Alpine, UMR 5553 CNRS-Université Joseph Fourier, BP 53 2233 Rue de la Piscine, Grenoble 38041, France
| | - Felix Breden
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Jacek Radwan
- Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland
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